From ff3ed25603d70f45fdce6c6063bdf1515316773f Mon Sep 17 00:00:00 2001
From: Olli Pettay <Olli.Pettay@helsinki.fi>
Date: Mon, 11 Jun 2018 22:11:16 +0300
Subject: [PATCH] Bug 1467920, ensure only non-negative values are reported to
 telemetry, r=mccr8

--HG--
extra : rebase_source : 09a804d5a4ee753c32a09c79c7bebe1ed85a5713
---
 dom/base/nsJSEnvironment.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index 025b767d7d01..2586aabcd4cc 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -1281,7 +1281,9 @@ FireForgetSkippable(uint32_t aSuspected, bool aRemoveChildless,
     if (!aDeadline.IsNull()) {
       if (aDeadline < now) {
         // This slice overflowed the idle period.
-        idleDuration = aDeadline - startTimeStamp;
+        if (aDeadline > startTimeStamp) {
+          idleDuration = aDeadline - startTimeStamp;
+        }
       } else {
         idleDuration = duration;
       }